Froth-flotation concentration of ores



Patented Sept. 22, 1925.

UNITED STATES- PATENT OFFICE.

CORNELIUS H. KELLER, OF SAN FRANCISCO, CALIFORNIA, ASSIGNOR TO MINERALSSEPARATION NORTH AMERICAN CORI'OBATION, OF NEW YORK, N. Y., A COB-IORATION O'I MARYLAND.

FROTH-FLOTATION CONCENTRATION OF ORES.

No Drawing.

To all (whom it may concern:

Be it known that I, CORNELIUS H. KELLER, a citizen of the United States,and a resident of San Francisco, county of San Fran-' cisco, State ofCalifornia, have invented certain new and useful Improvements inFroth-Flotation Concentration of Ores, of.

which the following is a specification.

This invention relates to the froth-flotation concentration of ores, andisherein described as applied to the concentration of certain ores withmineral-frothing agents in the presence of'certain organic compoundscontaining sulphur.

It has been found that certain sulphur derivatives of carbonic acidgreatly increase the efliciency of the froth-flotation process when usedin connection with mineralfrothing agents. The increased efliciencyshows itself sometimes in markedly better recoveries, sometimes ineffecting-the usual recoveries with greatly reduced quantities of theusual mineral-f'rothing agents, and

sometimes in greatly reducing the time needed for agitation to producethe desired recoveries.

The invention is herein disclosed in some detail as carried out withsalts of the sul- .phur derivatives of'carbonic acid containing anorganic radical, such as an alkyl radical, and known as xanthates, asthe new substance. These form anions and cations in solution. Excellentresults were also obtained by agitating ore pulps with the complexmixture produced when 33%% of pine oil was incorporated with analcoholic solution of potassium hydrate, and xanthates or analogoussubstances were produced by 40 adding carbon disulphide to this mixture.

The galena-bearing froth obtained with xanthates or analogous substancesused at the rate of 0.2 pounds per ton of ore had a characteristicbright sheen, like a plumbagohearing froth, and seemed to make a morecoherent froth than when other materials were used on the same ore.

In general the substances referred to are not mineral-frothingagents,producing only a sli ht scum, and some evanescent frothybublrles, when subjected to agitation which would producemineral-bearing froth on an ore pulp in the presence of amineralfrothing agent. The substances are efiecin concentratingApplication filed October 2a, 1923. 'Serial 110. 610,242.

tive in enabling a selective flotation of lead and zinc, and causeuncombined silver, if present, to tend to go into the lead concentraterather than with the zinc, where these are separated in separateconcentrates. Usually pre-agitation is unnecessary, thebrightening andother effects seeming to be practically instantaneous. The pulps may beeither acid, alkaline or neutral according to circumstances. Two sticksof caustic potash weighing perhaps 15 grams were partly immersed inabout 80 cc. of commercial carbon disulphide and kept for about ten daysin a closed bottle containing some air in the warm region of thelaboratory where were the hot plates used for drying. These eventuallyyielded a yellow or orange salt which was used with pine oil at the rateof approximately half a pound to a ton of ore Hibernia ore from TimberThe test was with Butte Mining (Jompany.

a neutral pulp, and the concentrates were seen to be clean withbrightened lead sulphide particles.

For laboratory purposes potassium xan thate was prepared as follows:

198.4 grams of 88.5% caustic potash was dissolved in 524 grams ethylalcohol (denatured #5 formula) at a temperature of 124 F., in a refluxcondenser. The solution was cooled to 58 F. It contained a large excessof alcohol over the theoretical amount needed for the subsequentreactions. To this was added, while stirring, and in a cooling bath, thetheoretical amount of carbon disulphide. The reaction was substantiallyinstantaneous, producing a thick pulp of potassium xanthate. The pulpwas cooled and centrifuged in a laboratory machine, yielding crystalscontaining about 20% moisture. The yield thus obtained was 74.7%.Another 17.5% was obtained 'by evaporation of the mother liquor. Boththe centrifuged crystals and the residue from the mother liquor gaveexcellent results in flotation. It was found in cases where sulphuricacid was used that the centrifuged material yielded better results thanthe uncentrifuged.

A pulp of Anaconda slimes which had been stored for several da sassaying 2.95% cop r (a part being oxi ed copper mineral was treatedwith cresylic acid as frothing agent and potassium xanthate, the latterused at the rate of half a pound to a ton of the slimes. With nopre-agitation, and fifteen minutes agitation in a laboratory subaerationmachine these slimes yielded a concentrate containing 15.6% copper, amiddling containing 0.48% copper and a tailing containing 0.082% copper.The small proportion of silver present was recovered in about the sameproportions. Similar results were obtained with the use of sodiumxanthate and General Naval Stores No. 5 flotation oil, a steam distilledpine oil.

A. pulp of Cash Mine ore subjected first to agitation for ten minuteswith a mixture of 0.3 pounds per ton of potassium xanthate with a smallproportion of a 10% or a saturated solution of naphthalene in xylene, toyield a lead concentrate, and then subjected to agitation for tenminutes with copper sulphate 0.2 pounds per ton, Barrett 1 flotation oil1.0 pound per ton, and General Naval Stores #5 flotation oil 0.1 poundsper ton, yielded the results shown in the following table. Attention iscalled to the recovery of 95% of the lead in a concentrate containing87% of the silver but containing only 5% of zinc, while 70% of the zincwas recovered in the zinc concentrate.

ico ore was agitated for ten minutes with potassium xanthate 0.15 poundsper ton and the same amount of coal tar creosote to yield a leadconcentrate. The remaining 0 pulp was agitated for fifteen minutes with0.2 pounds per ton of copper sulphate, 1.2 pounds per ton of water-gastar, and 0.05 pounds per ton of steam distilled pine oil. The resultsare shown in the following San Francisco Mines of Mexico. I

% Assays. Recoveries.

7 Ag. i (UL) Pb. Zn Ag Pb. Zn.

Heads 100. 0 l6. 5 9. 4 16. 1 12.2 67.0 64.0 12.0 49.4 83.2 9.1 28. 923. 6 3. 6 43. 4 41. 2 l1. 1 78. 0 Tails 58.9 4.5 1.5 6.0 9.4 5.7 12.9

Similar results were obtained with thisphate, 1.3 pounds Barrett No. 4:flotation oil,

and General Naval Stores No. 5 flotation oil 0.1 pounds, all per ton ofore, to yield a zinc concentrate.

During a seven and one-half hours run on current Anaconda slimes at therate of one hundred and eleven tons per twentyfour hours in a mineralseparation standard machine from a feed containing 3.28% copper, 0.26%being acid soluble copper, there was recovered a concentrate containing11.43% Cu. and 30.9% insoluble,-the latter being a proportion desirablefor smelting. The tailings contained 0.29%" copper of which 0.20% wasacid soluble copper. This test was run at a temperature of 82 F. usingfor reagents, 7.89 pounds of kerosene acid sludge, 21.6 pounds ofchamber sulphuric acid, 2.36 pounds of hard wood creosote, and 2.92pounds of a twenty per cent solution of potassium xanthate in water allquantities being in pounds per short ton or ore.

Anaconda old gravity. concentration tailings reground for flotation weretreated at the rate of four hundred and eleven tons per twenty-fourhours in a mineral separation standard machine provided with a porousbottom in the spitzkasten through which air was admitted. From a feedcontaining 0.52% copper, of which 0.12% was 0 acid soluble copper therewas recovered a concentrate containing 5.72% copper and 48% insolubles.The tailings from this contained 0.13% copper of which 0.08% was acidsoluble. This test was run at a temperature of 50 F. using for reagentsper ton of solids, 0.67 pounds of a 30% solution of potassium xanthatein water, 3.96 pounds of kerosene acid sludge, and 11.45 pounds ofchamber sulphuric acid.

Anaconda ore slimes containing 3.28" copper, of which 0.45% was acidsoluble, were subjected to froth-flotation concentration at 70 F. with7.8 pounds per ton of dry hydrated lime, 0.132 pounds per ton of steamdistilled pine oil, 0.38 pounds per ton of destructively distilled pineoil (G. N. S. #11 flotation), and 0.69 pounds per ton of potassiumxanthate in solution, yielding concentrates containing 13.76% copper and34.7% insolubles, with a tailing of 0.317% copper of which 0.173% wasacid soluble. This represented a recovery of 92.2%.

The lime was mixed with water and fed as a watery paste with the slimesto the first agitator of a series of nine standard minerals separationagitators or mixing compartments through which the pulp passed in seriesat the rate of 97 tons in 2 1 hours. The #11 pine oil was added at theseventh agitator, and 0.6 pounds per ton of the xanthate at the ninth.The pulp returned through fourteen spitzkastens, each equipped with aBrown aerator and circulating deyice. At the sixth spitzkasten thebalance of the xanthate was added. At the tenth spitzkasten the steamdistilled pine oil was added. The froth from the first nine spitzkastenswas collected as a finished concentrate, that from the remaining fivewas returned to'the first as a middling.

It has also been found thatfor the frothflotation concentrationofcertain ores, such as Calumet & Hecla, Britannia, Cananea andMoctezuma,. mother liquor obtained from centrifuging the above describedxanthates in the process of manufacture of said xanthates may be usedwith about the same proportions of mother liquor as of the xanthatecrystals specified with results as good or better than those abovegiven.

A pulp of 80 mesh Calumet and Hecla slimes containing 0.45% copper,mostly native, with considerable mineral occluded in the coarserparticles of gangue, was agitated five minutes 'with 0.3 poundspotassium xanthate, thenwas agitated for twenty min-- utes with 0.4pounds steam distilled pine 011, all per ton of ore. The concentratethus obtained was agitated for fiveminutes and 'the froth separated toform a finished concentrate, the remainder forming a middling. Theresults are shown in the following table:

Re Wt. Assays coveries Cu. Cu.

A' Chinese graphite ore containing 49% carbon as graphite, chiefly inamorphous state, ground to mesh, was agitated ten minutes with 0.2pounds potassium Xanthate and 0.15 pounds pine oil, both per ton of ore,yielding a froth concentrate and a tailing. The concentrate wasreagitated for five minutes to yield a finished concentrate andamiddling' The finished concentrate contained 72.8% carbon as graphite,the middling 36.8%, and the tailing 15.2%. These representedrespectively 79.2%, 10.2% and 10.6% of the original graphite content ofthe ore.

In the absence, of xanthate the same ore required a larger amount ofmineral-frothing agent and longer agitation to produce the same results.

Having thus described certain embodiments of the invention, what isclaimed is:

1. The process of concentrating ores which ore with a mineral-frothingagent and a sulphur derivative of carbonic acid adapted to form insolution anions and cations and adapted to co-operate with themineralfrothing agent to produce by the action of both a mineral-bearingfroth containing a large proportion of a mineral of the ore, saidagitationbeing so conducted as to form such a froth, and separating thefroth.

2. The process of concentrating ores which consists in agitating asuitable pulp of an ore with a inineral-frothing agent and a salt of asulphur derivative of carbonic acid adapted to form in solution anionsand cations and adapted to 'co-operate with the mineral-frothing agentto produce by the action of both a mineral-bearing froth containing alarge proportion of a mineral of the ore, said agitation being soconducted as to form such a froth, and separating the froth.

3. The process of concentrating ores which consists in agitating asuitable pulp of an ore with a mineral-frothing agent and a salt of an.alkyl sulphur derivative of carbonic acid adapted to co-operate withthe mineralfrothing agent to produce by the action of both amineral-bearing froth containing a large proportion of a mineral of theore, said agitation being so conducted as to form such a froth, andseparating the froth.

4. The process of concentrating ores which consists in agitating asuitable pulp of an ore with a mineral-frothing agent and a salt of anethyl-sulphur derivative of carbonic acid adapted to co-operate with themineralfrothing agent to produce by the action of both a mineral-bearingfroth containing a large proportion of a mineral of the ore, said atation being so conducted as to form such a froth, and separating thefroth.

5. The process of concentrating ores which consists in agitating asuitable pulp of an ore with a mineral-frothing agent and analkali-metal salt of an ethyl-sulphur derivative of carbonic acidadapted to co-operate with the mineral-frothing agent to produce by theactions of both a mineral-bearing froth containing a large proportion ofa mineral of the ore, said agitation bemg so conducted as to form such afroth, and sepa- I rating the froth.

6. The process of concentrating ores which consists in agitating asuitable pulp of an ore with a mineral-frothing agent and an alkalinexanthat-e adapted to co-operate with the mineral-frothing agent toproduce by the action of both a mineral-bearing froth containing a largeproportion of a mineral of the ore, said agitation being so conducted asto form such a froth, and separating the froth.

'Z. The improvement in the concentration of minerals by flotation whichcomprises subjecting the mineral in the form of a nonacid pulp to aflotation operation in the presence of a Xanthate.

8. The improvement in the concentration of minerals by flotation whichcomprises subjecting the mineral in the form-of a nonacid pulp to aflotation operation in the presence of potassium xanthate.

9. The improvement in the concentration of minerals by flotation whichcomprises subjecting the mineral in the form of a nonacid pulp to aflotation operation in the presence of a xanthate and a frothing agent.

10. The process of concentrating ores which consists in agitating asuitable pulp of an ore with a mineral-frothing agent and a sulphurderivative of carbonic acid containing an organic radical and adapted toco operate with the mineral-frothing agent to managers produce bearinfroth containing a large proportion of a mineral of the ore, saidagitation being so conducted as to form such a froth, and separating thefroth.

11. The process of concentrating ores which consists in agitating asuitable pulp of an ore with a mineral-frothing agent and a salt of asulphur derivative of carbonic acid containing an organic radical andadapted to co-operate with the mineralfrothing agent to produce by theaction of both a mineral-bearing froth, said agitation being soconducted as to form such a froth,

and separating the froth.

In testimony whereof, I have aflixed my 3 signature to thisspecification.

CORNELIUS H. KELLER.

by the action of both a mineral- 2

